<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>error404</title>
</head>
<body>
    <div id="app">
        ERROR 404
    </div>

    <style>
        body{
            padding: 80px;
            background: slategray;
        }
        #app{
            position: relative;
            width: 6em;
            color: whitesmoke;
            font-family: sans-serif;
            font-weight: bold;
            font-size: 50px;
            padding: 0.6em 0.4em;
        }
        #app::before,#app::after{
            content: "";
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            border: 0.2em solid orange;
            box-sizing: border-box;
            transform: rotate(45deg);
            box-shadow: 0.3em 0.3em 0.3em hsla(0,0%,35%,0.8);
        }
        #app::before{
            border-style: solid;
            z-index: -1;
        }
        #app::after{
            border-style: none solid solid;
        }

    </style>
</body>
</html>